Luis Carretero

This paper delves into conserved quantities of electromagnetic pulses, which are crucial for understanding their behavior. We introduce a precise framework for computing scalar properties (energy, helicity, and chirality) and vector properties (Poynting vector, Spin, and chirality flux) of electromagnetic pulses with gauge-invariant equations. Based on the far-field behavior of radiated electric field, our methodology offers accurate results akin to traditional volume integrals but at a lower computational cost. Additionally, our findings enable a reinterpretation of these properties as statistical average parameters of the pulse. This innovative approach not only simplifies calculations but also enhances their accuracy, making it useful for studying the main conserved quantities for complex electromagnetic field structures, as those formed by multiple interference of pulses.

We theoretically analyze the methodology for obtaining vectorial three-dimensional bullets, concretely Airy–Gauss bullets. To do this, binary micro zonal plates (BZP) were designed in order to obtain different Airy–Gauss bullets with sub-diffraction main lobe width. Following the vectorial diffraction theory, among the electrical field, we extend the theory to the magnetic field, and thus we analyze several properties such as the Poynting vector and the energy of Airy–Gauss vectorial bullets generated by illuminating the designed BZP with a temporal Gaussian circular polarized pulses.

Helicity and directionality control of scattered light by nanoparticles is an important task in different photonic fields. In this paper, we theoretically demonstrate that scattered light of lossy spherical nanoparticles excited by using two counter-propagating dephased plane waves with opposite helicity ±1 and the adequate selection of dephase and intensity shows a well defined helicity and a controllable scattering directivity. Numerical examples of Si nanospheres are studied showing their potential application to directional nanoantennas with a well defined helicity. The proposed method is valid for any type of nanoparticle, not only lossy ones.

A numerical analysis is carried out of the influence of the de-phasing parameter of an optical conveyor belt in the enantiomeric separation. The optical conveyor belt is obtained by the interference of a Laguerre Gaussian and a Gaussian beam with different beam waists, which are temporally de-phased. In order to obtain the maximum separation distance between enantiomers, we calculate the optimum range of values of the de-phasing parameter.

Chiral resolution is a fundamental problem in pharmaceutics or agrochemicals, so a great effort has been made to generate experimental techniques capable of producing mechanical separation of a mixture of enantiomers. Unlike other techniques that are usually employed, such as chiral resolving agents or chiral chromatography, we propose a new technique which is directly applicable in solution and without further processing. This technique is based on optical forces, since we show that with the proper design of the polarization states of the incident beams and temporal dephasing, a chiral sensitive optical conveyor can be obtained that is able to transport enantiomers in opposite directions. The implementation of such an optical conveyor with the required focused optical fields produces a well-defined trapping region for each enantiomer, since theoretical simulations over a large number of chiral particle trajectories show that it is possible to reach values of enantiomeric excess of over 99%.